A piezoelectric resonator that vibrates in a so-called width-expansion vibration mode includes a support frame that has, for example, a rectangular shape and a vibrating portion that is disposed in the support frame and that has, for example, a rectangular shape. The vibrating portion includes, for example, four vibration regions that are arranged in a row in a first direction, and stretching vibration, which entails repetitive expansion and contraction, in the first direction occurs as a result of electric fields having opposite phases being alternately applied to the adjacent vibration regions.
The vibrating portion is connected to the support frame by, for example, two pairs of support portions each extending in a second direction, which is perpendicular to the first direction. Each of the two pairs of support portions are respectively connected to, for example, the two adjacent vibration regions that are the inner vibration regions located between the other two vibration regions, which are the outer vibration regions positioned at the opposite sides in the first direction. Each of the support portions is connected to one of the end portions of the corresponding inner vibration region, each of the end portions being defined as a node point, that is, a minimum displacement point, and being located on a center line of the vibration region in the first direction.
Patent Document 1: U.S. Pat. No. 7,639,105,
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2008-228195,
It was found that, since the vibration regions are disposed on opposite sides of each of the adjacent inner vibration regions, as a result of each of the inner vibration regions being influenced by displacement of the vibration regions disposed on opposite sides thereof, neither of the end portions on the center lines of the inner vibration regions in the first direction serve as a node point. Consequently, even if the support portions are connected to the end portions on the center lines of the inner vibration regions, sufficient resonator characteristics are not obtainable.